worked on signal-strength-estimation

add this information to grid nodes
evaluate this information
new test-cases

sensors/radio/model/LogDistanceModel.h

@@ -0,0 +1,47 @@
+#ifndef LOGDISTANCEMODEL_H
+#define LOGDISTANCEMODEL_H
+
+#include <cmath>
+
+class LogDistanceModel {
+
+public:
+
+	/** convert from RSSI to a distance (in meter) */
+	static float rssiToDistance(const float txPower, const float pathLoss, const float rssi) {
+		return pow(10, (txPower - rssi) / (10 * pathLoss));
+	}
+
+	/** convert from a distance (in meter) to the expected RSSI */
+	static float distanceToRssi(const float txPower, const float pathLoss, const float distance_m) {
+		if (distance_m <= 1) {return txPower;}
+		return (txPower - (10 * pathLoss * std::log10(distance_m)));
+	}
+
+};
+
+#include <vector>
+
+class LogDistFastModel {
+
+private:
+
+	std::vector<float> lut;
+
+public:
+
+	LogDistFastModel() {
+		lut.resize(2000);
+		for (int i = 0; i < 2000; ++i) {
+			lut[i] = std::log10(i/10.0f);
+		}
+	}
+
+	float distanceToRssi(const float txPower, const float pathLoss, const float distance) const {
+		if (distance <= 1) {return txPower;}
+		return (txPower - (10 * pathLoss * lut[ (int) (distance*10) ]));
+	}
+
+};
+
+#endif // LOGDISTANCEMODEL_H

sensors/radio/model/WiFiModel.h

@@ -0,0 +1,18 @@
+#ifndef WIFIMODEL_H
+#define WIFIMODEL_H
+
+#include "../LocatedAccessPoint.h"
+
+/**
+ * interface for signal-strength prediction models
+ */
+class WiFiModel {
+
+public:
+
+	/** get the given access-point's RSSI at the provided location */
+	virtual float getRSSI(const LocatedAccessPoint& ap, const Point3 p) = 0;
+
+};
+
+#endif // WIFIMODEL_H

sensors/radio/model/WiFiModelLogDist.h

@@ -0,0 +1,31 @@
+#ifndef WIFIMODELLOGDIST_H
+#define WIFIMODELLOGDIST_H
+
+#include "WiFiModel.h"
+#include "LogDistanceModel.h"
+
+/**
+ * signal-strength estimation using log-distance model
+ */
+class WiFiModelLogDist : public WiFiModel {
+
+private:
+
+	float txp;
+	float exp;
+
+public:
+
+	/** ctor */
+	WiFiModelLogDist(const float txp, const float exp) : txp(txp), exp(exp) {
+		;
+	}
+
+	/** get the given access-point's RSSI at the provided location */
+	float getRSSI(const LocatedAccessPoint& ap, const Point3 p) override {
+		return LogDistanceModel::distanceToRssi(txp, exp, ap.getDistance(p));
+	}
+
+};
+
+#endif // WIFIMODELLOGDIST_H